An isolated DC-to-DC switching regulator or converter is an electronic circuit that converts a source of direct current (DC) from one voltage level to another without a galvanic connection between the input voltage domain and the output voltage domain. As overall system sizes shrink, miniaturization of DC/DC converters is required to fit within these systems. Inductive components are usually the bulkiest, and their size can be reduced by increasing the switching frequency as much as possible. Very High Frequency (VHF) switchers, operating in the range of 30˜300 MHz, require very accurate timing for driving power stage switches and precise synchronization for driving power devices.
Implementation of DC/DC converters in the VHF range enables the usage of miniaturized high-frequency transformers which can fit inside a conventional silicon package and which may be integrated. Due to the lack of a galvanic connection between the input and the output voltage domains, any communication must be transmitted across an isolated communication system and is usually based on opto-couplers or high voltage capacitors. The use of isolated communications makes the synchronization between primary side inverter and the secondary side rectifier even more challenging due to the cost and delay added by the communication channel. For these reasons, generating timing on one side of the isolation barrier, e.g., the primary side, and transmitting the timing to the other side, e.g. the secondary side, can be expensive and challenging. Moreover, the primary side does not necessarily have all the information necessary to generate the correct timing for optimal behavior of the secondary side.
In addition, VHF switchers are burdened by very large switching losses. In order to minimize these losses, it is advisable to achieve soft switching on the power devices, which in several DC/DC topologies requires setting the ON time of the power devices based on circuit parameters, such as operating switching frequency, transformer inductance, resonance, capacitance, etc. In many instances, the knowledge of passive components parameters is not known when designing the driver for the DC/DC converter. Even in the case of a system-in-a-package, where values of the passive components are known, these parameters are heavily affected by manufacturing tolerances, which can easily vary by 30 percent in either direction.